public class Example3_6{
 public static void main(String args[]){
  double sum = 0,item = 1;
  int i = 1,n = 20;
  while(i<=n){
   sum = sum+item;
   i = i+1;
   item = item*(1.0/i);
  }
  System.out.println("sum="+sum);
 }
}